Beginners garage conversion guide

There are different ways to add to the value of your home and space, with a loft conversion or house extension. Garage conversion in comparison is the quickest and most affordable conversion to increase living space. It can also add around 20% of the value to your home! This beginner’s guide to garage conversions explains everything you need to know.

Hdr, Garage, Old, Abandoned, Hall, Workshop, Factory
An example of a garage ready to be developed

Do you love your home but need more space? Is your garage just filled with junk or an empty unused space?

 Do you yearn for a larger kitchen/diner, a granny annex, more space for the children to play, a new bathroom, a home office space, maybe even a cinema room? Then a garage conversion is the most cost-effective conversion for you.

 More living space can be created from something that is already there, you just need someone with the skill and know-how to convert your garage for you. 

Compared to the costs involved in moving, garage conversion costs a lot less than moving, making it the ideal solution to create more living space. Moving can be very stressful. The children may have to change their school. Perhaps you have wonderful neighbours, and know the best places to eat in the area! Why put yourself through all that when you can have a garage conversion?

In this article, we can offer you guidance on how to convert your garage space, and a way to add to the value of your home. Please read on.

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Double garage conversion example

How much space will I get when I convert my garage?

A single garage can offer you up to 140 ft of extra space, expect to pay around £5,000 to £8,000, not bad for a new room and added value to your home!

A double garage may offer up to 240 ft of extra space, the garage conversion costs would be around £17,000. Enough room for a home office or a larger kitchen!

Please note these prices are a rough guide for converting a garage, and costs can vary depending on the finish required. Each conversion is unique!

Planning permission for garage conversions 

A single garage conversion rarely needs planning permission, so long as you are not extending or enlarging the garage and just converting a garage.

They generally fall under permitted development rights, which means planning permission is not needed, when doing a garage conversion within your home. When the garage conversion falls under a permitted development it is a good idea to apply for a lawful development certificate this would help things if you ever decide to sell or re-mortgage your home.

A building notice application does not need plans, it is quicker than a full plans application, and will allow work to start on some types of building work in your home, including a garage conversion, usually small building work. The notice can only be used on homes for living in. You can apply for a building application notice for a garage conversion from your local council or through a privately approved inspector. You do not get formal approval with a building notice as you would with the full planning application.

Why do I need building regulations?

When converting an existing garage you will need to apply to a local authority, for building control to send a building control officer, to make sure the garage conversion project meets the most current and up-to-date building regulation. The building control department will check for adequate doors and windows, good drainage, electric, fire safety, insulation, external walls, internal walls, and roofs within the garage conversion. Local building control will make sure your existing garage is converted to safe standards.

 A detached garage may require a full plans application for a garage conversion, it is always a good idea to check first with your local planning department to see if you need planning permission. You may have to apply for a change of use when doing a garage conversion on a detached garage. For instance, if your garage is to become a granny annex, this would be classed as a change of use when you convert your garage. 

If you are lucky enough to live in a conservation area, you will definitely need planning permission for a garage conversion when converting your garage. You should also check out to see if a parking space falls under planning conditions, as you might need to still have one available.

Can I convert my garage if it is a listed building?

If you own a property of this type you would need a full planning application for a garage conversion, and listed building consent is required, this is a legal requirement, it is illegal to build without this consent when converting your garage for an extra living room. The local council would need to consult historic England. You will also need to contact the local authority to apply for building regulations.

Party wall Act

The act covers the wall that separates homes, If you carry out building works on a neighbour’s wall whilst doing a garage conversion or any other type of build, without consent you are in theory trespassing!

The act does not affect the requirement for planning permission, or building regulations approval.

You will always need to have a neighbour’s consent in writing, if for example, you are going to be building on the boundary of the 2 properties, work to be done on a wall already there, or dig down and near to your neighbours foundations.

Notice of a party wall agreement must be given at least 2 months before work begins to those who may be affected by your garage conversion.

Examples of a sample letter are available to download at When you have completed a letter it should be given to your neighbour, with a booklet also available to download, explaining the act.


The walls, the roof, and foundations of the existing structure will need to be checked for any faults. This could add costs to the garage conversion if the garage is not sound. The foundations may need reinforcing to withstand the extra weight from your garage conversion, speak to your builder or structural engineer to find out if the foundations are suitable, there is the possibility a wall may need to be rebuilt or a new wall may need building.

The ceiling height may need to be raised, you need to allow 2-4m of ceiling height when the floor has been raised by 15cm above outside ground level.

The roof

Firstly the roof should be checked for its condition. The roof will need to be insulated if there is not a room above the garage in the main house. Building regulations cover the insulation process.

A flat roof can be insulated using either a warm roof or cold roof method. Flat roofs above an integrated garage are usually insulated with the warm roof method, the materials are fitted above the roof deck. This method maximises height space. The cold roof method is when the insulation goes below the roof deck. The cold roof method creates a cold space above the insulation, which can cause condensation.


You can employ an architect to design the garage conversion for you. An architect charges design fees around 5-12% of the total cost of the building works. An architect will have experience with building regulations, they may also have useful contacts in various trades. They may be able to put you in touch with a builder who specialises in garage conversions.

Alternatively, a builder will draw up plans and costs for you. This would be an effective way to save you money on design fees. Quite often people may decide to design the garage conversion with its new space in their home themselves.

Garage conversions can lead to quick decisions needing to be made, prepare yourself for making on-the-spot decisions.

Garage conversions can be less expensive if you come across a bargain say, for instance, an ex-display kitchen, or reduced-price furniture, fittings, and lighting. If you have the storage buy well in advance, and save money in the long run.

A kitchen built from reasonably priced units and then topped with an unusual, or expensive worktop and attractive handles, can potentially have a more expensive look to them without the heavy price tag. Clever lighting can enhance the overall look, either by placing lighting under units or directional at certain key areas, for instance, a picture on the wall.

Getting a quote

Find a builder who has the experience in the type of garage conversion you require, preferably one that specialises in garage conversions. Friends, family, or work colleagues are worth asking when it comes to finding recommendations.

Ask the builder for references, photos of work completed, to get an idea of their work standards. An architect works alongside builders frequently, is it possible to speak to a builder that the architect knows?

Always ask for an itemised quote, make sure the builder knows exactly what you would like done. A detailed set of plans and drawings can help the builder give you a more accurate quote.

A good builder can be booked up well in advance, this gives them the opportunity to pick their clients, therefore you need to be a client, who is organised and prepared, for them to want to work on your garage conversion for you.

Have a list ready, of everything you would like the builder to do, including tidying up and ask them to give you a quote that costs out everything you have listed for the garage conversion.

The building trade is unregulated, and your home is very important, therefore you should shop around to find the best builder to build your garage conversion. As a rule the larger the job the more quotes you should get.

Be prepared to be available to allow access for tradesmen into your home, during the garage conversion. Garage conversions require the expertise of various types of tradesmen.

Garage conversions can cause a little disruption to daily life, depending on how access is gained, you should prepare yourself for this. Try to plan ahead if you can, to make things as little disruptive as possible.

If you’re looking for a garage conversion in Essex, we can provide a free quote. Get in touch today.


This is done internally, generally, a stud wall will be fitted using wood, and left deep enough for insulation slabs to be put in.

If your garage conversion is detached your builder will possibly recommend external wall insulation. This will involve insulation boards being fitted and render systems to the external walls.

Damp proofing

A garage is not usually built as habitable as the main house, they are meant for vehicles, not people. It will need to have a damp proof course damp before the conversion can begin.

A damp proof course is a type of moisture control applied to walls and floors. The dampproof course will prevent moisture from getting into the garage.

The builder will treat damp walls in the garage and ensure they are dry before plastering. There are many ways of dealing with damp in a garage, it all depends on the type of garage walls, and how much money you have to spend on it.


The floor of the garage could be in need of being level. The floor will quite often be a concrete floor in a garage. The floor level can be raised at this point, if you are joining another room, during the garage conversion this will avoid a step. 

A damp proof membrane will need to be put down. The damp proof membrane can come in solid or liquid form, this is laid on top of the concrete floor of the garage. Liquid DPM is often best suited for garage conversions it is a liquid, damp-proof paintable membrane. The floor is then covered in screed which is around 75mm thick. Air bricks to the main house should not be blocked during this process of the garage conversion.

When you decided on the type of flooring you wanted, whether it is wood, tiles, or carpet, the builder will let you know at what point that these can be laid.

Doors and windows 

The old garage door will need to be removed, replacing the garage door with either brick, known as an infill wall the same as the house, or with windows and/ or a door. They need to suit the rest of the house. You will need to consider security, and ventilation once the garage door has been removed.

Keeping the doors and windows standard will help the build to be more cost-effective, however, if the budget allows why not go for something bold!

If the room you are creating does not have an escape route, then an escape window must be installed. The dimensions should be 450 mm and opens 0.33m2 and be no more than 1,000 mm from ground level. 

Heating and electrics

Always use professionals for safety reasons, and they will follow building regulations. 


A consumer unit otherwise known as a fuse box plays a major role in your home. It is responsible for controlling the electrical supply.

A new consumer unit could be required if new circuits are needed and the consumer unit already in use does not meet up-to-date regulations. When the work is completed you should receive an electrical installation certificate and a building control compliance certificate.

You may have to have new circuits installed, and the boiler could need to be upgraded, in which case expect to pay £2,000 approximately for an upgrade.

An electrician will allow an adequate supply for cookers and hobs, consider the type of lighting you require so that the electrician can make provision for them. 


Standard radiators are the most affordable option for a garage conversion, however, underfloor heating may free up precious wall space in a garage.

Underfloor heating is a form of heating and cooling system, which gives you climate control. This form of heating has no maintenance, there is no noise, it is easy to install, and most importantly it is energy efficient!

 There are two types of systems, electric or water-based, electric systems are easier and less disruptive to install. However, they are more expensive to run, it is probably best to use electricity in smaller rooms, such as a bathroom. The good news is an underfloor heating system should last up to 50 years!

Converting a garage to make a larger kitchen/diner is a popular option, with a new kitchen or bathroom allow for hot and cold water supplies and adequate drainage for dishwashers, and washing machines. This is not a difficult job to do, but it needs careful planning ahead.

Having an extractor fan installed is a quick and easy way to avoid any moisture build-up. Poor ventilation will cause dampness, which can be difficult to get rid of. Prices vary, higher quality fans will be more efficient and look more attractive than a cheaper fan. Bathroom extractor fans need to work harder, so you need to find a more powerful fan that can cope with the moisture levels. 

In summary

We hope you have found this article useful, remember to set yourself a manageable budget for your garage conversion, allow money for lighting, light switches. You would be surprised at how often these get forgotten about when costing for things. 

Should you have any questions or queries please do not hesitate to drop us an email. We aim to respond as quickly as possible.

Good luck with your garage conversion!

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